IJSPT CASE REPORT ABSTRACT

Transcription

1 IJSPT CASE REPORT UTILIZATION OF AUTOREGULATORY PROGRESSIVE RESISTANCE EXERCISE IN TRANSITIONAL REHABILITATION PERIODIZATION OF A HIGH SCHOOL FOOTBALL-PLAYER FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION: A CASE REPORT Aaron D. Horschig, DPT, CSCS, USAW 1 Travis E. Neff PT, ATC, CSCS 1 Ambrose J. Serrano, MA, CSCS, USAW 2 ABSTRACT Background and Purpose: The Autoregulatory Progressive Resistance Exercise (APRE) model of periodization is an effective form of resistance training programming for short-term training cycles in healthy athletic populations that has yet to be effectively described in literature in application for rehabilitation purposes. The purposes of this case report are to: 1) review the periodization concepts outlined in the APRE model, 2) to detail the use of the APRE periodization programming through the rehabilitation of a high school football player using the back squat exercise after anterior cruciate ligament reconstruction (ACLR) and 3), to examine the applicability of this method in the transitional period from skilled rehabilitation to strength and conditioning for which a current disconnect exists. Case Description: Starting at 20 weeks post-operatively, a 17-year-old male high school football player recovering from ACLR was able to show a 10 lb daily average increase with the 10 RM protocol, a 6 lb daily average increase during the 6RM protocol, and a 6.3 lb average increase with the 3RM protocol. Outcomes: A two-repetition maximum of 390 lbs was performed in the back squat at the conclusion of the program at 39 weeks post-operatively. Discussion: The results of this case report strengthen the current limited knowledge regarding periodization during the later phases of rehabilitation and the transition back to sport participation time period, while at the same time providing new insights for future protocol considerations in rehabilitating athletes. The APRE method of periodization provides an individualized progressive resistive protocol that can be used to safely and effectively increase strength in both healthy populations and individuals recovering from injury during short-term training cycles. Levels of Evidence: Therapy, Level 4-Case report Key Words: Back squat, periodization, physical therapy 1 Boost Physical Therapy & Sports Performance, Lee s Summit, MO, USA 2 Lake Placid Olympic Training Center, Lake Placid, NY, USA CORRESPONDING AUTHOR Aaron D. Horschig, DPT, CSCS, USAW Physical Therapist at Boost Physical Therapy & Sports Performance 1254 SE Century Drive Lee s Summit, MO (314) Fax: (816) Aaron@boostkc.com The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 691

2 BACKGROUND AND PURPOSE The concept of periodization, defined as a systematic planned variation of program variables in a training program, has been well established in literature to be more effective in eliciting strength, body composition improvements and other performance goals than non-periodized programs both in healthy, injured, trained, and untrained individuals. 1,2,3,4,5,6 Synonymous with phrase Training Organisation, the utilization of periodization is not a recent development, with many texts on the subject appearing as early as A periodized program optimizes the principles of specific adaptation to imposed demands (SAID) and the progressive resistance method (PRE) in order to more efficiently promote desired outcomes such as increased strength or muscular hypertrophy through the continual adaptation responses of the neuromuscular system. 7,8 By introducing progressively overloading stressors to the body, the neuromuscular system will adapt and develop towards the targeted fitness goals, provided the systematic progressing load stressors are adequate and do not exceed the adaptive capabilities of the body. 7 However, once the body has adapted to the added stressor, strength increases are no longer seen. 8 Simply stated, periodization continually changes the type of stressors placed on the neuromuscular system, thereby avoiding a plateau and promoting continued adaption and strength gains. An early training programming model used to systematically improve strength was reported in literature in 1945 by DeLorme, who proposed a method consisting of multiple sets in which patients lifted their 10 repetition maximum (RM). 9 Eventually this protocol evolved to a three set system of progressing heavier loads for 10 repetitions; referred to as progressive resistance exercise (PRE). 9 This has since been the starting point for the development and study of numerous periodization concepts such as classical linear periodization (LP), which emphasizes a breakdown of the training program into time periods or training cycles of macrocycles (9-12 months), mesocycles (3-4 months) and microcycles (1-4 weeks) with ever fluctuating changes in volume and intensity. 8,10,11 Other popular forms of non-linear periodization include undulating models, as described by Poliquin, in which programming variables such as volume and intensity are changed more frequently such as on a daily or weekly basis. 12 The concept of Daily undulating periodization (DUP) has been shown to elicit greater strength gains in short-term training cycles (12 weeks) when compared to LP models equated for similar volume and intensity. 8,13 Although there is a consensus in the literature on benefits of periodized vs non-periodized programming when it comes to eliciting the most efficient strength and performance gains, large inconsistencies remain regarding which type of periodized model is most efficient. 14 This dilemma is even more complicated when taking into account the training level of the subject and time frame allowed for training programming. An even greater gap in evidence exists in periodization protocols that are specific for the injured and rehabilitating athlete that facilitate the most efficient neuromuscular adaptations while being mindful of the healing processes taking place at the biological level. 15 Most literature on strength training periodization is based on healthy and not rehabilitating subjects. 15 Current popular protocols for rehabilitation periodization emphasize the principles of DeLorme s PRE through LP and non-linear protocols. 15,16 Complicated with the common inability to assess a patient s 1 repetition maximum (1RM) secondary to rehabilitation contraindications, especially post-operatively, many clinicians are left with presupposed approaches for determining the appropriate program variables to facilitate maximal efficient performance gains. Even after discharge from rehabilitation, many practitioners and strength and conditioning coaches often resort to using a bestguess approach during the transition period where a subject is no longer injured or in need of skilled rehabilitation, however, is not yet displaying his or her pre-injury strength and still re-acquiring strength through neuromuscular adaptations at a different rate than healthy subjects. These athletes are many times blindly thrust back into their prior training programs with little attention given towards a needed personalized individualized periodized protocol. The quick return to prior training programs is many times based on a flawed premise that the athlete, once given the cleared medical status, is without question ready to resume their exact high-level prior training regime. It was not until 1979 when a variant of the DeLorme system, known as the Daily Adjustable Progressive The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 692

3 Resistance Exercise (DAPRE) method, was successfully integrated into rehabilitation programming by Knight. 17 This method allowed, for the first time, an interactive protocol to objectively determine either the optimal time to increase resistance or the optimal amount of weight to increase the resistance during a resistance exercise, thus providing a more efficient way to rehabilitate strength by accounting for individualized reacquisition of strength. 2 A specific autoregulatory program by Siff, derived from the DAPRE method, expanded on this concept in order to meet different training goals of hypertrophy and strength/power, and allow for continual body adaptation through the SAID principle. 7 This method, termed Autoregulatory Progressive Resistance Exercise (APRE), enhances the previous DAPRE method by introducing training cycles aimed at improving hypertrophy, strength and power regimes of conditioning. This allows for continual neuromuscular adaptation to systematically changing program variables thus promoting efficient performance gains. 7 To the authors knowledge, only one study has compared the effectiveness of the APRE method to another periodization model. When compared to a traditional LP model, the APRE method of periodization has been shown to be more effective in increasing the strength and strength-endurance of healthy subjects in both the bench press and squat over a short period of 6 weeks. 14 There is, however, no evidence in literature supporting or documenting the use or effectiveness of the APRE concept during the rehabilitation process of the injured athlete. The purposes of this case report are to: 1) review the periodization concepts outlined in the APRE model, 2) to detail the use of the APRE periodization programming through the rehabilitation of a high school American football player using the back squat exercise after anterior cruciate ligament reconstruction (ACLR) and 3), to examine the applicability of this method in the transitional period from skilled rehabilitation to strength and conditioning for which a current disconnect exists. Case Description The patient was an active 17-year-old male American high school football player with a history of ACLR of his dominant right lower extremity. Mechanism for original injury was a non-contact deceleration and pivot movement during a football game. Magnetic resonance imaging (MRI) of the lower extremity revealed a complete anterior cruciate ligament (ACL) rupture. The patient completed initial conservative rehabilitation and was able to return to finish his season wearing a functional knee brace until eventually undergoing ACL reconstruction surgery using a bone patellar tendon bone (BTB) autograft along with a partial lateral meniscectomy, after the end of the season. Time from initial injury to date of surgery was approximately 15 weeks. During his return to football before ACL reconstruction surgery, the patient had no reported episodes of giving-way however reported feeling unstable and weak during single leg tasks. The patient s post-operative rehabilitation process was unremarkable without any complications utilizing traditional evidence-based rehabilitation clinical protocol guidelines. 18 Criteria during early phase rehabilitation included restoring knee active range of motion (AROM), quadriceps strengthening (both with isometric and closed chain kinetic exercises, such as mini-squats), restoring patellar mobility, diminishing swelling and pain, and restoring safe independent ambulation. Later phases of rehabilitation continued the trend towards increasing intensity and complexity of functional strengthening while incorporating strength and conditioning principles such as power development, balance and proprioception training. He received medical release to return to running at 16 weeks post-operatively and was able to return to full athletic participation by 30 weeks. For the purpose of this case report, the details of his rehabilitation protocol other than the APRE programming for the back squat exercise, which began at 20 weeks post-operatively, are not included, as the entirety of the rehabilitation process is not the specific focus of this case report. Informed consent was obtained from the subject indicating approval for data collection for the purpose of publication. Clinical Impression #1 It was determined that the patient was a good choice to utilize the APRE intervention secondary to the need to return to his prior high level of strength in an efficient manner. Because he was a high school football player he would be required to perform high intensity squats during team strength and conditioning sessions The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 693

4 and up until this point he had only performed very light intensity squats during rehabilitation exercises with higher repetitions. Prior to the start of the APRE periodization, the patient had been progressing from squats while holding a weighted kettle bell (45 lbs) for 3-5 sets of repetitions and had transitioned to using the weightlifting bar for back squats of light intensity (135 lbs) for 3-5 sets of 10 repetitions. For this reason an efficient method of strength periodization was needed in order to help the patient return to higher intensity squatting. Examination At 20 weeks post-operatively the patient was able to meet the developed criteria for initiation of the APRE program, including observed lower extremity symmetry within 90% (ACLR compared to opposite lower extremity) using the 1) Star Excursion Balance Test (SEBT) and 2) a lateral step down excursion test. 19,20 The SEBT has been shown to be an effective test in analyzing postural and lower extremity control deficits. 20 The patient also had to demonstrate correct technique in the barbell back squat. 21 It is important to note that any lower extremity symmetry of less than 90% compared to the opposite lower extremity would prohibit the start of the APRE program for the reason that a considerable amount of skilled therapy to enhance neuromuscular control would still be needed before progressing to a protocol that emphasizes strength/power. The back squat method utilized during the protocol was a high bar technique with shoulder width stance. The athlete was given verbal and tactile cues to slowly descend to a parallel position where the hip and knee joints were even, and then extending the hips and knees simultaneously during the ascension phase without leaning forward or showing unwanted hip rotation. The athlete wore only standard cross-training shoes and did not wear any additional supporting equipment during any of the squatting sessions such as belts, lifting suits, knee wraps, or weightlifting shoes. Clinical Impression #2 Based on the patients ability to show sufficient lower extremity symmetry on all examination testing previously discussed, it was determined that he met the requirements to start the APRE periodization for the back squat exercise at 20 weeks post operative. Outcome The APRE method employs a 10 RM scheme for hypertrophy, a 6 RM scheme for strength/hypertrophy, and finally a 3 RM scheme for strength/power. 7 All routines are based on the DeLorme method of PRE and consist of 4 sets of different load and repetition requirements (Table 1). 7 The 10 RM regime will be described here as it was the first periodization scheme employed for this case report for the back squat exercise. After the performance of a general warm up including 10 minutes cycling on a recumbent bike followed by 5 minutes of self-myofascial release using foam rolling to the anterior and lateral lower extremities, the first set consisted of 12 repetitions at 50% of the estimated 10 RM (also labeled the working set as the first two sets are percentages taken from set 3). After a minimum 2-minute rest period, the first set was followed by 10 repetitions at 75% of the same-estimated 10 RM. During the third set, the anticipated 10 RM was lifted until failure. Due to this programming being used for rehabilitation and transition purposes, failure was not only seen as the inability to complete another repetition, but also the inability to continue with good technique secondary to lower extremity compensations or the presence of pain. For this reason, the clinician overseeing the performance at times made subjective decisions to end the set secondary to technique deficits that began to appear. The number of repetitions reached during this maximal effort third set was then used to adjust the intensity for the fourth and last set (Table 2). Again, repetitions during the fourth set were performed to maximum effort, and the number of repetitions reached was used similarly after the previous third set in order to determine the anticipated 10 RM working set for the next training session by adding or subtracting loads (Table 2). This allows subjects to Table 1. Adjusted Progressive Resistance Exercise Training Routines. Set 3 RM Routine 6 RM Routine 10 RM Routine 0 Warm-up Warm-up Warm-up 1 6 reps (50% of 3 RM) 10 reps (50% of 6 RM) 12 reps (50% of 10 RM) 2 3 reps (75% of 3 RM) 6 reps (75% of 6 RM) 10 reps (75% of 10 RM) 3 Reps to failure (3 RM) Reps to failure (6 RM) Reps to failure (10 RM) 4 Adjusted reps to failure* Adjusted reps to failure* Adjusted reps to failure* *Denotes that the training load must be adjusted according to Table 2 The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 694

5 Table 2. Example Adjustments for APRE Protocols. Adjustments for 3 RM Adjustments for 6 RM Adjustments for 10 RM Repetitions Set 4 Repetitions Set 4 Repetitions Set Decrease Decrease Decrease Same 3-4 Decrease 0-5 lbs 7-8 Decrease 0-5 lbs 5-6 Increase Same 9-11 Same 7+ Increase lbs 8-12 Increase Increase Increase lbs 17+ Increase lbs exercise near their optimal capacity for strength during each training session allowing for individualized progression of strength redevelopment. 2 It should be noted that rest periods between sets are subjective based on the patients perceived fatigue. It is recommended by the authors that a minimum 2 minutes of rest, maximum of 5 minutes, be utilized between the maximum repetition sets. The 10 RM scheme was used during 6 training days over a 3-week period, each spaced at least 2 days apart for adequate recovery. For the purpose of this case report, strength changes seen during the APRE protocol are reported as the performance changes seen between the first and last day of each separate repetition protocol (Figure 3). After the 3-week protocol was complete, a de-loading week was employed consisting of 3 sets of 10 repetitions at 75% of the last estimated 10RM for two training sessions. The 6RM protocol was then initiated for a 3-week period, again consisting of 6 training periods spaced at least 2 days apart. The second de-load week was employed after finishing the 6RM protocol, this time consisting of 3 sets of 5 repetitions at 75% of the last 6RM estimate. The last 3RM scheme of the APRE used a 3-week cycle with 5 training sessions. Overall, the APRE program was able to emphasize 3 distinct phases of hypertrophy, strength/hypertrophy, and strength/power (Table 4). At no time during the protocol did the athlete experience pain, which would have limited his ability to perform continued repetitions. Table 3 contains tabulated results for the back squat performance changes seen with the APRE. Through the 10RM protocol, a 50 lb increase in strength was shown (21.3% improvement) in a 3-week period consisting of 6 workouts. A daily average increase of was seen (4.3% improvement) with a weekly average increase of 17.5 lbs with the 10 RM protocol. During the 6RM protocol, a 30 lb increase was seen (9.7% improvement) in a 3-week period consisting of 6 workouts. A daily average increase of 6 lbs (1.9% improvement) was shown with a weekly average increase of 12.5 lbs (4% improvement). During the 3 last weeks of the APRE program, the 3RM protocol yielded a 25 lb increase (6.9% improvement) over 5 workouts. A 6.3 lb daily average increase (1.7% improvement) was shown with a 13.8 lb weekly average increase (3.8% increase). The last day the patient was able to perform a 390 lb back squat for 2 repetitions 32 weeks post-op ACLR. This weight of 390 lbs was only 100 lbs less than his prior 1 repetition maximum prior to tearing his ACL. Table 3. APRE Repetition and loads for Subject. APRE Rep Scheme Number of Sessions First Day Last Day Strength Increases (4 th Set) 3 rd Set 4 th Set 4 th Set Change (%) Daily Average (lbs) Change (%)* Weekly Average (lbs) Change (%)* 10 RM 6 Weight (lbs) Repetitions RM 6 Weight (lbs) Repetitions RM 5 Weight (lbs) Repetitions *Denotes change from the irst day weight lifted The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 695

6 Table 4. Overall APRE Training Program with associated phase empahsis APRE Rep Active Weeks Emphasis of Phase Scheme 10 RM 1,2,3,4* Hypertrophy 6 RM 5,6,7,8* Strength/Hypertrophy 3 RM 9,10 Strength/Power * Weeks 4 & 8 were de-load weeks, but still performed the repetitions designated in the speci ic phase DISCUSSION The concept of periodization, defined as a systematic planned variation of program variables in a training program, has been well established in literature to be more effective in eliciting strength, body composition improvements and other performance goals than non-periodized programs both in healthy, injured, trained or untrained individuals. 1,2,3,4,5,6 There is abundant literature on periodization protocols and their effectiveness in healthy trained and untrained subjects as it relates to all aspects of fitness, not only strength. However a paucity of evidence can be found in relation to rehabilitation protocols, especially when searching for protocols for effective and safe ways to return an athlete to a high level of sport and resistance training performance post-operatively. Consistency in descriptions of specific programming variables is lacking amongst clinical protocols in which effective rehabilitation can be carried out while still being mindful of individual differences in biological and neuromuscular healing processes. 15,22 Rehabilitation periodization protocols exist outlining both linear and non-linear programming approaches, which make good recommendations for exercise selection and even volume, however, they lack in specifics for exercise intensity. 15 For example, with the linear periodization following ACL reconstruction proposed by Lorenz et al, the protocol load requirements are generally vague per volume requirements, and may not be as effective for that reason in promoting the reacquisition of strength in power athletes that need to return to high intensity resistance exercises such as the back squat. 15 The DeLorme protocol of PRE was the first reported periodization model in research literature to detail a systematic model for increasing strength both in healthy and injured populations. 9 The DAPRE method by Knight, modified from the original DeLorme PRE, allowed for the first time an interactive protocol for objectively determining either the optimal time to increase resistance or the optimal amount of weight to increase the resistance during an exercise, thus providing a more efficient way to rehabilitate strength in an individualized and safe manner. 2 The APRE used in the present case report, varies only slightly from the DAPRE in that it provides multiple training protocols within itself based on specific desired outcomes. There is a 10 RM scheme provided for improving hypertrophy, a 6 RM scheme for addressing strength/ hypertrophy, and finally a 3 RM scheme for development of strength/power. 7 In a rehabilitation setting or in a strength and conditioning setting for the transition athlete who has been discharged from a traditional rehabilitation setting however has not yet returned to pre-injury strength levels, this allows for continual neuromuscular adaptation to systematically changing program variables thus promoting efficient performance gains. 7 Where as the DAPRE method has only been shown in literature with non-functional seated knee extension strengthening exercises after knee injury, the APRE method has been shown in healthy populations to be an effective periodization method when used with functional strengthening exercises such as the back squat compared to LP programming during short (6 week) training programs. 2,14 Mann et al was able to show significant improvements in 1RM bench press, number of repetitions performed with a weight of 225 lbs in the bench press (strength/endurance) and in estimated 1RM back squat (APRE: / lbs vs LP 8.4 +/ lbs, p = 0.05) compared to a LP group over a 6-week training period. 14 The results of this case report are consistent with the findings of Mann et al, showing significant changes in estimate RM back squat strength using the APRE protocol in a short training cycle (Table 3). 14 The APRE protocol used in this case report allowed for weeks of de-loading between the three stages. This principle of using de-loading weeks, called the fluctuating overload system, has been used to facilitate recovery and growth between stages of increased loading of a microcycle. 7 It has been recommend that if maintaining a LP program model during the rehabilitation after ACLR, strength training should be the emphasis between the The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 696

7 12 th to 16 th week before employing the power phase in the later weeks of the rehabilitation process. 15 For the authors purposes, the APRE programming regime for the back squat was not incorporated into the rehabilitation protocol until the 20 th week post-operatively. The 20 th post-operative week was deemed, in the authors opinion, to be an important transitional period when the patient had been medically released to return to partial participation in athletics and weight training, yet had not re-acquired strength levels prior to ACLR. The athlete had been utilizing numerous forms of resisted squatting exercises in the rehabilitation protocol such as hand-held kettle bell squats and band resistance squats up until the point when the APRE was initialized. It is important to note some physician post-operative protocols restrict strengthening of the involved lower extremity for many weeks, thus, the initiation of the APRE protocol would need to be delayed until proper prerequisites for the start were met. There are several limitations to this case report; one being that the results are only based on the strength increases of one patient during the rehabilitation process. More research should be performed with patients rehabilitating from similar injuries with a control group of athletes using other LP or DUP programs in order to fully assess the effectiveness of each protocol. The results of this case report do not suggest that the APRE protocol is superior to LP or DUP programming, however show that strength can be gained in a healthy individual and re-acquired during rehabilitation and in the transition phase after formal rehabilitation in a quick and safe manner during short-term training cycles. Conclusion During the transition period after skilled physical rehabilitation, athletes may find themselves returning to resistance training with strength deficits compared to pre-injury levels. This results of this case report demonstrate the outcomes following the use of a detailed, individualized periodized protocol that was used safely and effectively for this athlete in a rehabilitation and transition period in order to increase his back squat performance in a short time period. REFERENCES 1. Baker D, G. Wilson, & Carolyn R. Periodization: The effect on strength of manipulating volume and intensity. J Strength Cond Res. 1994;8: Knight K. Quadriceps strengthening with the DAPRE technique: case studies with neurological implications. Am College of Sports Med. 1985;17(6): Stone, MH, O Bryant H, & Garhammer J. A hypothetical model for strength training. J Sports Med Phys Fitness. 1981;21: Stone MH, O Bryant H, Garhammer J, McMillan J, & Rozenek R. A theoretical model of strength training. Strength Cond J. 1982; Stowers, T., McMillan J., Scala D., Davis, V., Wilson, D., & Stone, M. The short-term effects of three different strength-power training methods. Strength Cond J. 1983;5: Willoughby DS. The effects of meso-cycle length weight training program involving periodization and partially equated volumes on upper and lower body strength. J Strength Cond Res. 1993; 7: Siff MC. Supertraining. Denver, Co: Supertraining Institute; Rhea MR, Ball SD, Phillips WT, & Burkett LN. A comparison of Linear and Daily Undulating Periodized Programs with Equated Volume and Intensity for Strength. J Strength Cond Res. 2002;16(2): Rhea MR, Phillips WT, Burkett LN, et al. A comparison of linear and daily undulating periodized programs with equated volume and intensity for local muscular endurance. J Strength Cond Res. 2003;17: Baechle T & Earle R. Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics, Rhea MR, Phillips WT, Burkett LN, et al. A comparison of linear and daily undulating periodized programs with equated volume and intensity for local muscular endurance. J Strength Cond Res. 2003;17: Poliquin C. Five steps to increasing the effectiveness of your strength training program. Strength Cond J. 1988;10: Prestes J, Frollini AB, De Lima C, et al. Comparison between linear and daily undulating periodized resistance training to increase strength. J Strength Cond Res. 2009;23(9): Mann JB, Thyfault JP, Ivey PA, & Sayers SP. The Effects of autoregulatory progressive resistance exercise vs linear periodization on strength improvements in college athletes. J Strength Cond Res. 2010;24(7): Lorenz DS, Reiman MP, & Walker JC. Periodization: Current Review and Suggested Implementation for The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 697

8 Athletic Rehabilitation. Sports Health. 2010;2(6): Reiman MP, Lorenz DS. Integration of strength and conditioning principles into a rehabilitation program. Int J Sports Phys Ther. 2011;6(3): Knight K. Knee rehabilitation by th daily adjustable progressive resistive exercise technique. Amer J Sports Med. 1979;7(6): Wilk KE, Macrina LC, Cain EL, Dugas JR, & Andrews JR. Recent advances in the rehabilitation of anterior cruciate ligament injuries. J Orthop Sports Phys Ther. 2012;42(3): Chmielewski TL, Hodges MJ, Horodyski M, Bishop MD, Conrad BP, & Tillman SM. Investigation of clinician agreement in evaluating movement quality during unilateral lower extremity functional tasks: a comparison of 2 rating methods. J Orthop Sports Phys Ther. 2007;37(3) Herrington L, Hatcher J, Hatcher A, & McNicholas M. A comparison of star excursion balance test reach distances between ACL deficient patients and asymptomatic controls. The Knee. 2009;16: Fortin JD & Falco FJ. The biomechanical principles of preventing weightlifting injuries. Physical Medicine and Rehabilitation: State of the Art Reviews. 1997;11(3) Beynnon BD, Uh BS, Johnson RJ, et al. Rehabilition after anterior cruciate ligaement reconstruction: a prospective, randomized, double-blind comparisoin of programs administered over two different time intervals. Am J Sports Med. 2005;33: The International Journal of Sports Physical Therapy Volume 9, Number 5 October 2014 Page 698